The objectives of the present study were to assess whether resistant plants maintained the normal timing of leaf senescence during grain filling and to examine the physiological effects of any leaf senescence traits that were affected by infection.
The susceptible allele possibly accelerated the progress of leaf senescence within a normal onset period; therefore, the maintenance of a higher photochemical efficiency in PSII is a direct and important factor in protection of yield against Pst infection.
However, D. noxia feeding does not induce total breakdown of the chloroplast, (Haile et al., 1999; van der Westhuizen et al., 1998a) and feeding-induced chlorosis differs from normal chlorophyll degradation that occurs during leaf senescence (Ni et al., 2001; Wang et al., 2004a).
Phenotypic analyses of Atg7 mutants indicates that Atg7 disruption renders Arabidopsis (Arabidopsis thaliana) cells hypersensitive to a shortage of nutrients with features of premature leaf senescence, though the mutant is otherwise normal (Doelling et al., 2002).
Finally, as the homolog of AtNAP in rice, OsNAP can restore the delayed leaf senescence phenotype in atnap mutant to a normal WT phenotype [ 10].
In general, leaf senescence is dependent on age and developmental stage under normal conditions and in the absence of external stress, and the leaf yellowing during senescence is usually observed in old leaves.
There are growing evidences, suggesting that autophagy plays critical roles in the processes of plant development under normal conditions such as leaf starch degradation, root cell growth, rubisco degradation during leaf senescence, programmed cell death (PCD) of suspensor in somatic embryos of Picea abies, and maintenance of peroxisomal quality.
Prolonged deficits cause leaf senescence, ripening delays, and carryover effects.
In general, leaf senescence was extended under warming, whereas the post-fruit leaf stage was shortened under cooling (Fig. 3).
Lim, P. O., Woo, H. R. & Nam, H. G. Molecular genetics of leaf senescence in Arabidopsis.
