Li Chunjie

Stress tolerance mechanisms of 6 native plant species growing in China's northern grassland and their utilization

It is a long term work to assemble the knowledge needed to utilize the rich native plant resources to assist social and economic development in China. The progress of the research results and their application of mechanisms underlying the stress-tolerance in native plants including Zygophyllum xanthoxylum, Artemisia sphaerocephala, Microula sikkimensis, Achnatherum inebrians, Cleistogenes songorica and Leymus chinensis were reviewed in this paper. The main results and findings are as follows: based on discovering the physiological mechanism of drought tolerance of Z. xanthoxylum, the key genes involved in drought tolerance were cloned and applied into the genetic improvement of important legume forage lucerne (Medicago sativa) and lotus (Lotus corniculatus); the desert shrub A. sphaerocephala and alpine species M. sikkimensis contain high contents of polyunsaturated fatty acids, the highest contents being found in the seeds; the diversity of drunken horse grass fungal endophyte symbiont was investigated on a national scale. The alkaloids produced by the symbiont are the main reason for both increased plant stress tolerance and the toxicity symptoms observed after intake by grazing animals; the biological, physiological and molecular genetic characteristics of C. songorica were studied. As a result, the species is expected to be domesticated successfully. Technical information on procedures for pasture establishment and seed production of this species has been developed; the seed dormancy mechanisms of L. chinensis were explored, and techniques to effectively break dormancy were developed.

Effects of Achnatherum inebrians infected with Neotyphodium endophyte on accompanying species of Stipa capillata and Poa sphondylodes.

Drunken horse grass(Achnatherum inebrians),an intoxicating grass in native grasslands of Northwest China,often grows in conjunction with Stipacapillataand Poa sphondylodes.Competitive interactions between endophyte infected(E+)A.inebrians and endophyte free(E-)A.inebrians with S.capillataand P.sphondylodes were investigated.E+A.inebrians had a significant inhibition effect on percentage seed germination and seedling growth(P0.05),which declined significantly by 17.1%,13.6%,respectively.Similarly,seedling length declined 23.2%and by 16.3%;E+ plants had significant inhibition effects on tiller heights of S.capillataand P.sphondylodes from the first week after germination(P0.05)and on tiller numbers and total biomass(P0.05).E-A.inebrians had no significant effects on seed germination,seedling growth,tiller height,tiller number or total biomass(P0.05).S.capillataand P.sphondylodes had no significant effects on A.inebrians.In summary,E+A.inebrians showed significant antagonism to S.capillataand P.sphondylodes,but E-A.inebrians had no significant effects on the other two grasses.