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Wissuwa, M.

Publications and source records attributed to Wissuwa, M..

2 recordsLinked to original sources
bioRxiv2024

A DJ123 allele at the heading date quantitative trait locus qHd7.1 promotes early heading without yield penalties under natural short-day and low fertility conditions in Madagascar

QTL analysis of heading date (Hd) was performed using a recombinant inbred line population derived from a cross between rice cultivars IR64 and DJ123. Phenotypic data was obtained from sites in Japan and Madagascar differing in photoperiod and soil fertility. The Japan site had long-days (LD) and high fertility, while the Madagascar site had short-days (SD) and low fertility conditions. Under LD in Japan, we discovered two Hd QTL on chromosome 7, qHd7.1 and qHd7.2, whereas only one of these (qHd7.1) was detected under SD conditions in Madagascar. RILs carrying DJ123 alleles at both QTLs headed 9.5 days earlier in Japan (LD) compared to IR64 alleles, whereas the effect of DJ123 alleles at qHd7.1 under SD conditions of Madagascar was 4 days and a combined effect of qHd7.1 and qHd7.2 did not exist. In Madagascar, early heading did not carry a yield penalty, whereas it caused reduced grain yield in Japan. These results suggest that RILs harboring the DJ123 allele of qHd7.1 have high yield potential and good adaptation to low fertility conditions in Madagascar and that this can be achieved in a shortened cultivation period, improving resilience to effects of climate change for African rice farmers.

plant biology↗
bioRxiv2024

Comparative root transcriptome analysis suggests down-regulation of nitrogen assimilation in DJ123, a highly phosphorus-efficient rice genotype

Many cultivable lands across the globe are characteristically low for plant-available phosphorus (P). This necessitates application of P fertilisers, but this increases farming costs beyond the affordability of marginal farmers. Thus, developing cultivars with high P-use efficiency (PUE) is necessary in high-yielding modern rice varieties, which are typically inefficient in P usage. However, the molecular and physiological bases to increase PUE in crops remain elusive. Here, we studied root transcriptomes of two breeding parents contrasting in PUE via RNA-seq to elucidate key physiological and molecular mechanisms that underlies efficient use of P in rice. Examination of transcriptome data obtained from plants grown under P-sufficient and P-deficient hydroponic conditions in DJ123 (an upland rice genotype adapted to low P soils) and IR64 (a modern rice variety less efficient in P use) revealed that the genes encoding nitrogen assimilation-related enzymes such as glutamine synthetase [EC. 6.3.1.2], glutamate synthase [EC. 1.4.1.13], and asparagine synthetase [EC. 6.3.5.4] were down-regulated only in DJ123 roots while it was not significantly affected in IR64 under low P conditions. In addition, DJ123 roots had a lower total nitrogen (N) concentration than IR64 irrespective of P conditions. Taken together, we surmise that the low level of N concentration together with down-regulation of the N assimilation-related genes allow DJ123 to operate at a low level of N, thus leading to formation of root tissues with lower metabolic investment and a greater PUE.

plant biology↗