Biology Reference
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5. CONCLUSIONS AND FUTURE PERSPECTIVES
The lily ASR is induced through desiccation-associated ABA signaling
transduction in the pollen. We propose a dual role for LLA23, as a regulator
and a protective molecule, upon exposure to water deficits. A genome-
wide microarray and promoter analysis suggests a strong association in the
expression of stress-responsive genes among ASR-overexpressing, sugar and
drought treatments and highly inducible genes also exist in each specific
stress treatment. Considerable progress in our understanding of the func-
tions of ASR in plants has been made in the past two decades. However,
the intrinsic lack of structure of ASR and the mechanism by which LLA23
communicates between the cytoplasm and the nucleus coupled with the
occurrence of masking processes that allow LLA23 to remain in the cyto-
plasm should warrant further investigation.
Gene expression is organized in a hierarchy, the top of which is governed
by a regulatory transcription factor. Many transcription factors govern the
expression of stress-responsive genes, either cooperatively or independently,
in controlling plant growth upon various stresses. ASR functions as a func-
tional protein (osmoprotectant) and a regulator of many important pro-
cesses, such as signaling and hormone responses, carbohydrate and protein
metabolism, cytoskeletal organization, and defense and abiotic responses.
Importantly, these advances would help clarify the organization of poorly
understood signaling network and sugar-based regulation and coordina-
tion of carbohydrate and protein metabolism in plants. Clearly, more of
these signaling partners need to be isolated and investigated to uncover the
multiple regulatory layers in each signaling pathway, including the targeting
components of ASR at the cellular and subcellular levels, and the various
amplifications of the signal through different effectors.
Our understanding of the molecular mechanisms that underlie various abi-
otic stresses has improved considerably because of the development of advanced
technologies that allow the study of transcription factor function on a genome-
wide scale. The results obtained from our microarray analysis paved the way
for more thorough investigations into the molecular mechanisms underlying
drought-, sugar-, and ASR-induced signaling. However, as with all microarray
analyses, the interpretation of the transcript changes requires caution because
the changes in mRNA levels may not correlate with the changes in protein or
enzyme activity levels. Furthermore, although microarray analysis is sensitive in
signal detection, it only provides a transient snapshot of gene expression.
 
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