Estimating divergent forest carbon stocks and sinks via a knife set approach.

Forest carbon stocks and sinks (CSSs) have been widely estimated using climate classification tables and linear regression (LR) models with common independent variables (IVs) such as the average diameter at breast height (DBH) of stems and root shoot ratio. However, this approach is relatively ineffective when the explanatory power of IVs is lower than that of unobservable variables. Various environmental and anthropogenic factors affect target variables that cause the correlation between them to be chaotic. Here, we designed a knife set (KS) approach combining LR models and the wandering through random forests (WTF) algorithm and applied it in a specific case of Phyllostachys edulis (Carrière) J. Houz. (P. edulis) forests, which have an irregular relationship between their belowground carbon (BGC) stocks and average DBH. We then validated the KS approach performed by cluster computing to estimate the aboveground carbon (AGC) and BGC stocks and the total net primary production (TNPP). The estimated CSSs were compared to the benchmark of the methodology that applied Tier 1 in the Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories via 10-fold cross validation, and the KS approach significantly increased precision and accuracy of estimations. Our approach provides general insights to accurately estimate forest CSSs relying on evidence-based field data, even if some target variables are divergent in specific forest types. We also pointed out the reason why current fancy models containing machine learning (ML) or deep learning algorithms are not effective in predicting the target variables of certain chaotic systems is perhaps that the total explanatory power of observable variables is less than that of the total unobservable variables. Quantifying unobservable variables into observable variables is a linchpin of future works related to chaotic system estimation.

Proteomic and comparative genomic analysis of two Brassica napus lines differing in oil content.

Ultrastructural observations, combined with proteomic and comparative genomic analyses, were applied to interpret the differences in protein composition and oil-body characteristics of mature seed of two Brassica napus lines with high and low oil contents of 55.19% and 36.49%, respectively. The results showed that oil bodies were arranged much closer in the high than in the low oil content line, and differences in cell size and thickness of cell walls were also observed. There were 119 and 32 differentially expressed proteins (DEPs) of total and oil-body proteins identified. The 119 DEPs of total protein were mainly involved in the oil-related, dehydration-related, storage and defense/disease, and some of these may be related to oil formation. The DEPs involved with dehydration-related were both detected in total and oil-body proteins for high and low oil lines and may be correlated with the number and size of oil bodies in the different lines. Some genes that corresponded to DEPs were confirmed by quantitative trait loci (QTL) mapping analysis for oil content. The results revealed that some candidate genes deduced from DEPs were located in the confidence intervals of QTL for oil content. Finally, the function of one gene that coded storage protein was verified by using a collection of Arabidopsis lines that can conditionally express the full length cDNA from developing seeds of B. napus.

Involvement of alternative oxidase in the regulation of sensitivity of Sclerotinia sclerotiorum to the fungicides azoxystrobin and procymidone.

Sclerotinia sclerotiorum is a filamentous fungal pathogen that can infect many economically important crops and vegetables. Alternative oxidase is the terminal oxidase of the alternative respiratory pathway in fungal mitochondria. The function of alternative oxidase was investigated in the regulation of sensitivity of S. sclerotiorum to two commercial fungicides, azoxystrobin and procymidone which have different fungitoxic mechanisms. Two isolates of S. sclerotiorum were sensitive to both fungicides. Application of salicylhydroxamic acid, a specific inhibitor of alternative oxidase, significantly increased the values of effective concentration causing 50% mycelial growth inhibition (EC50) of azoxystrobin to both S. sclerotiorum isolates, whereas notably decreased the EC50 values of procymidone. In mycelial respiration assay azoxystrobin displayed immediate inhibitory effect on cytochrome pathway capacity, but had no immediate effect on alternative pathway capacity. In contrast, procymidone showed no immediate impact on capacities of both cytochrome and alternative pathways in the mycelia. However, alternative oxidase encoding gene (aox) transcript and protein levels, alternative respiration pathway capacity of the mycelia were obviously increased by pre-treatment for 24 h with both azoxystrobin and procymidone. These results indicate that alternative oxidase was involved in the regulation of sensitivity of S. sclerotiorum to the fungicides azoxystrobin and procymidone, and that both fungicides could affect aox gene expression and the alternative respiration pathway capacity development in mycelia of this fungal pathogen.

Involvement of alternative oxidase in the regulation of growth, development, and resistance to oxidative stress of Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum is a cosmopolitan, filamentous, fungal pathogen that can cause serious disease in many kinds of crops. Alternative oxidase is the terminal oxidase of the alternative mitochondrial respiratory pathway in fungi and higher plants. We report the presence of this alternative pathway respiration and demonstrate its expression in two isolates of S. sclerotiorum under unstressed, normal culture conditions. Application of salicylhydroxamic acid, a specific inhibitor of alternative oxidase, severely inhibited the mycelial growth of S. sclerotiorum both on potato dextrose agar plates and in liquid culture media. Inhibition of alternative oxidase could influence the growth pattern of S. sclerotiorum, as salicylhydroxamic acid treatment induced obvious aerial mycelia growing on potato dextrose agar plates. Under the treatment with salicylhydroxamic acid, S. sclerotiorum formed sclerotia much more slowly than the control. Treatment with hydrogen peroxide in millimolar concentrations greatly decreased the growth rate of mycelia and delayed the formation of sclerotia in both tested S. sclerotiorum isolates. As well, this treatment obviously increased their alternative pathway respiration and the levels of both mRNA and protein of the alternative oxidase. These results indicate that alternative oxidase is involved in the regulation of growth, development, and resistance to oxidative stress of S. sclerotiorum.

Cytological and molecular characterization of a novel monogenic dominant GMS in Brassica napus L.

A novel genic male sterile (GMS) line in Brassica napus L., which was identified in 1999, was found to be controlled by a monogenic dominant gene, which we have designated as MDGMS. The microspores of the MDGMS abort before the degradation of the tapetal cell layer. The F1 fertility from any fertile lines crossed with MDGMS segregated and the ratio was close to 1:1. Bulked segregation analysis (BSA) was employed to identify random amplified polymorphic DNA (RAPD) markers linked to the Ms gene in MDGMS. Among 880 random 10-mer oligonucleotide primers screened against the bulk DNA of sterile and fertile, one primer S243 (5'-CTATGCCGAC-3') gave a repeatable 1500-bp DNA polymorphic segment S243(1500) between the two bulks. Analysis of individual plants of each bulks and other types of GMS and cytoplasmic male sterility (CMS) lines suggest that the RAPD marker S243(1500) is closely linked to the MDGMS locus in rapeseed. This RAPD marker has been converted into sequence characterized amplified region (SCAR) marker to aid identification of male-fertility genotypes in segregating progenies of MDGMS in marker-assisted selection (MAS) breeding programs.

[Molecular markers linked to mono-dominant genic male sterile gene in rapeseed (Brassica napus L.)].

Bulked segregant analysis (BSA) was used to identify randomly amplified polymorphic DNA (RAPD) markers linked to the MS gene in mono-dominant GMS of rapeseed (Brassica napus L.), which was bred by Hybrid Rapeseed Research Center of Shaanxi Province. A total of 300 random 10-mer oligonucleotide primers were screened on the DNA from fertile and sterile bulks. Primer S(243) (5'CTATGCCGAC3') gave identical 1.5 kb DNA polymorphic segment OPU-03(1500) in the bulk S, but not in the bulk F (Fig.2). The DNAs from individual plants of each bulk and from their sister lines, which were generated from the same original crossing, were then screened with the primer S(243), and the same results were obtained (Figs.3,4). Other types of GMS and CMS were analyzed using primer S(243), and the specific 1.5 kb DNA segment was not found (Fig.5). Therefore, the RAPD marker OPU-03(1500) is linked to the mono-dominant GMS trait in rapeseed. This RAPD marker OPU-03(1500) was cloned into a T-easy vector and sequenced. The sequence here obtained was highly homologous to one of the Arabidopsis DNA sequences. According to this DNA conserved region in different species, we designed a pair of specific primers P1 (5'ATGTCGCTGAGGCCG-AGCAC3') and P2 (5'GGCACACTGTCACG-ATCCTTGG3') and amplified only one specific 2.3 kb DNA fragment in each bulk. There are two mutant loci between the two DNA fragments after sequencing. We designed another pair of specific primers P3 (5'CTCCAGCAGCAGCAGC-AGCCT3') and P4 (5'GCAGGAATGAGAA-CCGTAGG3') according to the DNA sequence at the mutant loci. A specific DNA segment was amplified only in the fertile line but not in the sterile line using the primers P3 and P4 (Fig.6). Therefore the RAPD marker were converted into SCAR marker. Moreover, the SCAR marker detection method was improved (Fig.7).