The antennal transcriptome analysis and characterizations of odorant-binding proteins in Megachile saussurei (Hymenoptera, Megachilidae).

BACKGROUND: Odorant-binding proteins (OBPs) are essential in insect's daily behaviors mediated by olfactory perception. Megachile saussurei Radoszkowski (Hymenoptera, Megachilidae) is a principal insect pollinating alfalfa (Medicago sativa) in Northwestern China. The olfactory function have been less conducted, which provides a lot of possibilities for our research. RESULTS: Our results showed that 20 OBPs were identified in total. Multiple sequence alignment analysis indicated MsauOBPs were highly conserved with a 6-cysteine motif pattern and all belonged to the classic subfamily, coding 113-196 amino acids and sharing 41.32%-99.12% amino acid identity with known OBPs of other bees. Phylogenetic analysis indicated there were certain homologies existed among MsauOBPs and most sequences were clustered with that of Osmia cornuta (Hymenoptera, Megachilidae). Expression analysis showed the identified OBPs were mostly enriched in antennae instead of other four body parts, especially the MsauOBP2, MsauOBP3, MsauOBP4, MsauOBP8, MsauOBP11 and MsauOBP17, in which the MsauOBP2, MsauOBP4 and MsauOBP8 presented obvious tissue-biased expression pattern. Molecular docking results indicated MsauOBP4 might be the most significant protein in recognizing alfalfa flower volatile 3-Octanone, while MsauOBP13 might be the most crucial protein identifying (Z)-3-hexenyl acetate. It was also found the lysine was a momentous hydrophilic amino acid in docking simulations. CONCLUSION: In this study, we identified and analyzed 20 OBPs of M. saussurei. The certain homology existed among these OBPs, while some degree of divergence could also be noticed, indicating the complex functions that different MsauOBPs performed. Besides, the M. saussurei and Osmia cornuta were very likely to share similar physiological functions as most of their OBPs were clustered together. MsauOBP4 might be the key protein in recognizing 3-Octanone, while MsauOBP13 might be the key protein in binding (Z)-3-hexenyl acetate. These two proteins might contribute to the alfalfa-locating during the pollination process. The relevant results may help determine the highly specific and effective attractants for M. saussurei in alfalfa pollination and reveal the molecular mechanism of odor-evoked pollinating behavior between these two species.

[Effects of different water harvesting modes on alfalfa planting in semi-arid areas of Northwest China].

A field experiment with complete random design was conducted to investigate the effects of different mulching materials [common plastic film (CMR), biodegradable mulch film (BMR), and soil crust (SR)] and different ratios of furrow to ridge (60 cm:30 cm, 60 cm:45 cm, and 60 cm:60 cm) on the runoff efficiency, soil water storage, soil water content, and hay yield and water use efficiency of alfalfa in semiarid areas of the Loess Plateau. The runoff efficiency in treatments SR, BMR, and CMR was 32.0%, 90.7%, and 96.4%, respectively. In the early growth period of alfalfa (from April to June) , the soil water storage between the treatments had no significant difference, but in the late growth period (from July to September), the soil water storage in CMR and BMR was significantly higher than that in SR. The soil water storage in SR was significantly higher than that in traditional planting (TP). At budding stage, the soil water storage in TP, SR, BMR, and CMR was 223.27, 248.56, and 277. 81, and 284.16 mm, respectively. In the whole growth period, the hay yield of alfalfa in TP, SR, BMR, and CMR was 4112.1, 3397.5, 4317.8, and 4523.8 kg x hm(-2), and the water use efficiency was 11.08, 10.48, 14.56, and 14.95 kg x mm(-1) x hm(-2), respectively. The ratio of furrow to ridge had no significant effects on the water use efficiency in the same treatments. When the ratio of furrow to ridge was 60 cm:44 cm, the hay yield in CMR and BMR reached the maximum.

[Effects of exogenous nitric oxide on the growth and nitrogen metabolism of alfalfa seedlings under salt stress].

In order to explore the regulation approaches for improving the salt-tolerance of alfalfa, the seedlings of Medicago sativa L. cv. Gannong No. 4 were taken to study their growth and nitrogen metabolism under salt stress as affected by NO-donor SNP, NO-scavenger c-PTIO, and sodium ferrocyanide (a SNP analogue with NO not released). Exogenous NO could obviously alleviate the inhibition effects of salt stress on the seedling growth and photosynthesis via increasing plant dry matter and leaf chlorophyll content, net photosynthesis rate, transpiration rate, and soluble protein content. Exogenous NO enhanced the activities of leaf nitrate reductase, glutamine synthetase, and glutamate-oxoglutarate aminotransferase, restrained the activities of protease and glutamate dehydrogenase, decreased the free amino acid content, and improved the nitrate content and ammonium assimilation under salt stress. Applying sodium ferrocyanide did not show any alleviation effect on the seedling growth and nitrogen metabolism under salt stress. As a NO-scavenger, c-PTIO inhibited the growth and nitrogen metabolism under salt stress, but the inhibition effect could be mitigated by supplementing SNP. It was suggested that exogenous and endogenous NO were involved in the regulation of alfalfa nitrogen metabolism under salt stress.

[Livelihood status assessment of farmers and herdsmen's households based on participatory appraisal: a case in Taipusi Banner of Inner Mongolia].

Participatory appraisal method was adopted to investigate the recent livelihood status of different type farmers and herdsmen's households in the Taipusi Banner of Inner Mongolia agriculture- animal husbandry ecotone, aimed to understand their livelihood strategies and restricting factors and to search for the ways to improve their living standards. The households dealing with pure agricultural production had smaller family size, with older age-structure and lower educational level, and their simple livelihood strategies brought about larger vulnerability and risk. To introduce and expand non-agricultural activities would be the important way to promote the livelihood diversification and to reduce the livelihood risks of these households. The households dealing with pure animal husbandry took grazing as the main subsistence, and their production activities were greatly restrained by the pasture vulnerability. To develop environment-friendly and high-yielding agriculture and animal husbandry would be the effective way to solve the livelihood problems of these households and to protect the ecological environment. The households dealing with both agricultural production and business or dealing with both animal husbandry and business generally had larger family size, with younger age- structure, higher diversity in labor division, larger proportion of non-farming activities, and better living standards. Especially for the households dealing with both animal husbandry and business, their income was much higher.