Alleviation of arsenic toxicity by phosphate is associated with its regulation of detoxification,defense,and transport gene expression in barley

Arsenic(As) contamination in soils has posed a severe threat to safe crop production. The previous studies showed the antagonism between phosphorus(P) and As in plant growth and As uptake, while the mechanisms of alleviating As toxicity by P is not completely clear. Due to the limiting P condition, it is imperative to understand how low P addition can be used to suppress arsenate As(V) uptake and the subsequent mechanisms involved. Thus in this study we investigated the effect of P addition on As uptake, anti-oxidative enzyme activity, and anti-oxidant content, and the relative expression of transport, defense, and detoxification genes using two barley genotypes differing in As toxicity tolerance. P addition significantly reduced As concentration in plant tissues, and caused the great changes in activities of catalase and superoxide dismutase, glutathione content, and the relative expression of examined genes when the plants of the two barley genotypes were exposed to 100 μmol L^(–1) As, with ZDB160(As-tolerant) being much more affected than ZDB475(As-sensitive). The current results show that P addition can alleviate As toxicity by regulating the expression of As transport, defense, and detoxification genes to a greater extent in As tolerance of barley, suggesting the possibility of controlling As uptake and toxicity by applying low amount of P fertilizers in the As-contaminated soils.

Development of Heat Tolerant Two-Line Hybrid Rice Restorer Line Carrying Dominant Locus of OsHTAS

In order to create novel germplasm resources for breeding heat tolerant variety,we transferred a dominant allele OsHTAS,previously characterized and cloned from a high-temperature tolerant local variety HT54,which was collected from the rice production area of southern China,into a high-temperature sensitive intermediate breeding line HT13 through six rounds of successive backcross by using marker-assisted selection.The molecular analysis showed that the recovery of genetic background of a resultant near isogenic line(NIL),MHT13,was around 99.8%.The OsHTAS gene introduced in the MHT13 expressed normally in the HT13 genetic background,mediating heat tolerance and phenotype similar to those of the donor parent HT54.The major agronomic traits of MHT13 resembled those of the recurrent parent HT13.Moreover,MHT13 had high general combining ability and its rice quality reached the grade 3 standard of edible high-quality rice issued by Ministry of Agriculture of the People’s Republic of China,which greatly improved its application value in rice production.