Arbuscular Mycorrhizal Fungus Species Dependency Governs Better Plant Physiological Characteristics and Leaf Quality of Mulberry (Morus alba L.) Seedlings.

Understanding the synergic interactions between arbuscular mycorrhizal fungi (AMF) and its host mulberry (Morus alba L.), an important perennial multipurpose plant, has theoretical and practical significance in mulberry plantation, silkworm cultivation, and relevant textile industry. In a greenhouse study, we compared functional distinctions of three genetically different AMF species (Acaulospora scrobiculata, Funneliformis mosseae, and Rhizophagus intraradices) on physiological and growth characteristics as well as leaf quality of 6-month-old mulberry seedlings. Results showed that mulberry was AMF-species dependent, and AMF colonization significantly increased shoot height and taproot length, stem base and taproot diameter, leaf and fibrous root numbers, and shoot and root biomass production. Meanwhile, leaf chlorophyll a or b and carotenoid concentrations, net photosynthetic rate, transpiration rate and stomatal conductance were generally significantly greater, while intercellular CO2 concentration was significantly lower in AMF-inoculated seedlings than in non-AMF-inoculated counterparts. These trends were also generally true for leaf moisture, total nitrogen, all essential amino acids, histidine, proline, soluble protein, sugar, and fatty acid as they were significantly increased under mycorrhization. Among these three tested AMFs, significantly greater effects of AMF on above-mentioned mulberry physiological and growth characteristics ranked as F. mosseae > A. scrobiculata > R. intraradices, whilst on mulberry leaf quality (e.g., nutraceutical values) for better silkworm growth as F. mosseae ≈A. scrobiculata > R. intraradices. In conclusion, our results showed that greater mulberry biomass production, and nutritional quality varied with AMF species or was AMF-species dependent. Such improvements were mainly attributed to AMF-induced positive alterations of mulberry leaf photosynthetic pigments, net photosynthetic rate, transpiration rate, and N-containing compounds (methionine, threonine, histidine, and proline). As a result, application of Funneliformis mosseae or A. scrobiculata in mulberry plantation could be a promising management strategy to promote silkworm cultivation and relevant textile industry.

Localization of S genes on extended DNA fibers (EDFs) in Brassica oleracea by high-resolution FISH.

The compactness of plant chromosome and the structures of plant cell wall and cytoplasm pose a great resistance to fluorescence in situ hybridization (FISH), and consequently many new methods for improving spatial resolution are being exploited to overcome these problems. However, for plants with small chromosomes like rice and Brassica, there are still many difficulties. In this article a new and effective technique for preparation of extended DNA fibers (EDFs), using a series of treatments to prophase I chromosomes of Brassica oleracea PMCs, is presented. This technique allows longitudinal extension of the chromosomes 30-107 times longer than those of their metaphase counterparts. The length of the extended DNA fibers is between 89 microm and 273 microm, and the space resolution is 42.8-53.0 kb. Stretching ratios were assessed in a number of FISH experiments with super-stretched chromosomes from meiotic prophase I nuclei of B. olerecea. Through FISH to EDFs of pachytene chromosomes hybridized in situ with SRK (S-locus receptor kinase) and SPII (S-locus protein II) probes, for the first time we localized the accurate positions of S-locus and quantitatively analyzed the features of S genes in B. oleracea genome to show all S genes were single-copied. In addition, the length between two linked genes was measured to be about one micron. As a result, the highest space resolution which was about 4 kb was obtained.

[Progress of molecular mechanism of self-incompatibility in Brassica].

In recent years certain progress in Brassica signaling was reviewed about some self-compatibility-related genes such as SRK, SLG, SCR, ARC1, THL1 and THL2. Meanwhile, molecular mechanism in Brassica self-compatibility signaling was reviewed, including its action models.