SUMMARYThe predicted 2–4°C increment in temperature by the end of the 21st Century poses a threat to rice production. The impact of high temperatures at night is more devastating than day-time or mean daily temperatures. Booting and flowering are the stages most sensitive to high temperature, which may sometimes lead to complete sterility. Humidity also plays a vital role in increasing the spikelet sterility at increased temperature. Significant variation exists among rice germplasms in response to temperature stress. Flowering at cooler times of day, more pollen viability, larger anthers, longer basal dehiscence and presence of long basal pores are some of the phenotypic markers for high-temperature tolerance. Protection of structural proteins, enzymes and membranes and expression of heat shock proteins (HSPs) are some of the biochemical processes that can impart thermo-tolerance. All these traits should be actively exploited in future breeding programmes for developing heat-resistant cultivars. Replacement of heat-sensitive cultivars with heat-tolerant ones, adjustment of sowing time, choice of varieties with a growth duration allowing avoidance of peak stress periods, and exogenous application of plant hormones are some of the adaptive measures that will help in the mitigation of forecast yield reduction due to global warming.

Differential localization of decarboxylation and carboxylation in association with Kranz anatomy distinguish species with C 4 or C 3 -C 4 intermediate photosynthesis from species with C 3 photosynthesis. Moricandia nitens has a C 3 -C 4 intermediate photosynthetic mechanism and yet is closely related to C 3 Brassica species. In order to introduce the C 3 -C 4 character from M. nitens into Brassica crops, sesquitetraploids (MACC) were synthesized by crossing Brassica napus (AACC) and a somatic hybrid (M. nitens + B. oleracea, MMCC). Homologous fragments (2966 and 3254 bp) of P-protein gene of glycine decarboxylase (gdcP) were isolated from M. nitens and B. napus, respectively, to develop a PCR-based marker for assisted selection. Reverse transcriptase-polymerase chain reaction (RT-PCR) of the partial encoding regions of both gdcPs indicated that the mRNAs were expressed in the expanded leaf. The characterization of high divergence, but with large conserved island in the regulatory region of the two C 3 species, implies that they may play an important role in maintaining the C 3 photosynthetic pathway. Thereafter, a dominant gene-specific marker was developed within the highly divergent region for subsequent introduction of C 3 -C 4 photosynthesis from Moricandia nitens into Brassica crops.

Abstract. The medicinal plant Fritillaria thumbergii was confirmed for the first time as a new host of Potato leafroll virus (PLRV) by reverse-transcription polymerase chain reaction (RT-PCR). This is the first report of Fritillaria thumbergii as a host of PLRV in China.

No abstract