Abstract:
Drought is the leading single factor that limits maize production thus inhibiting the crops genetic potential. In
response to drought, maize and other plants synthesize Poly ADP-Ribose (PAR) protein. This process is controlled by the Poly
ADP-Ribose Polymerase (PARP) genes and consumes cellular energy, leading to plant death. This study evaluated four tropical
inbred maize (Zea mays L.) lines; CML 216, CML 144, A04 and E04 for their response to growth limiting water stress and
their relative expression of PARP2 gene under drought and non-drought conditions. The leaf lengths and growth rates of the
fourth leaf were monitored for 21days post emergence while fresh and dry weights of drought stressed and non-stressed
seedlings were recorded a month after emergence of the fourth leaf. The relative expression of PARP2 gene was determined
using rtPCR after isolating RNA from drought stressed and non-stressed maize seedlings. There was no significant difference
in the mature lengths of the fourth leaf in the four genotypes when the maize seedlings were not subjected to drought and when
subjected to severe drought stress. However, subjecting maize seedlings to mild drought resulted in a significant difference in
the mature leaf lengths based on the different genotypes (P= 0.0066). The growth rate of maize seedlings based on the fourth
leaf was observed to be affected by drought, with a higher mean growth rate (1.74 cm day-1) registered in seedlings which were
not subjected to drought and those subjected to moderate drought (1.78 cm day-1). A slower growth rate (1.37 cm day-1) was
observed in seedlings subjected to severe drought stress. Fresh and dry weights of maize seedlings were also observed to be
significantly different based on the level of drought exerted (P = < 0.0001) and the genotype (P = < 0.0001). The expression of
PARP2 gene was found to be directly proporti
